@inproceedings { santos11, booktitle = {in Advances in Artificial Life, ECAL 2011: Proceedings of the Eleventh European Conference on the Synthesis and Simulation of Living Systems,}, keywords = {Game Theory;Multi-Agent Societies;}, publisher = {MIT press}, title = {Co-evolution of pre-play signaling and cooperation}, year = {2011}, author = {Francisco C. Santos and Jorge M Pacheco and Brian Skyrms} }